Field of the Invention
The present invention relates to a position detection apparatus, an imprint apparatus, and a method for manufacturing a device.
Description of the Related Art
An imprint technology which is a technology that transfers a minute structure on a mold to a workpiece such as a resin or a semiconductor substrate has gained attention in recent years. The imprint technology can mass-produce semiconductor devices at low cost without needing a large-scale device such as a vacuum process, and the like.
In the imprint technology, a workpiece formed by applying the resin onto a substrate in advance is prepared. As the resin, for example, a photo-curable resin or a thermosetting resin can be used. The resin on the substrate contacts a mold having a desired uneven pattern to fill the uneven pattern with the resin. The resin is cured through ultraviolet-light irradiating or heating while the resin and the mold contact each other. Thereafter, the cured resin and the mold are released from each other, and as a result, the uneven pattern is transferred to the workpiece.
As an alignment method of the substrate and the mold, a method discussed in on Japanese Patent Application Laid-Open (Translation of PCT Application) No. 2006-516065 has been known. Light diffracted by a diffraction grating formed on the mold and a diffraction grating formed on the substrate is detected to measure a relative position between the substrate and the mold.
However, in a position detection apparatus discussed in Japanese Patent Application Laid-open (Translation of PCT Application) No. 2006-516065, the light diffracted by the diffraction grating of the mold is diffracted by a diffraction grating on a wafer. Light intensity received by a sensor is reduced by twice diffraction. In particular, since the diffraction grating on the wafer is formed by a wafer process, a surface step is not present or a minute step is formed, and a layer absorbing alignment light may be formed even on an upper layer of a mark, and diffraction efficiency remarkably deteriorates. Since the intensity of the alignment light is determined by multiplying diffraction efficiency of the diffraction grating of the mold by the deteriorated diffraction efficiency, the intensity of the alignment light received by the sensor deteriorates. When the intensity of the alignment detection light is decreased, an influence of electric noise of a detector and the like causes measurement precision of alignment to deteriorate.